Fuel cells (e.g., polymer electrolyte membrane fuel cells) are an alternative to internal combustion engines in a significant number of transportation vehicles. Conventional fuel cells include a pair of opposing flow plates, an anode and a cathode between the flow plates, and a membrane between the anode and the cathode. The anode includes a catalyst configured to split the hydrogen fuel source into hydrogen ions and electrons. The cathode includes a catalyst configured to utilize available electrons to split the oxygen in the oxidizer source into negative oxygen ions. The membrane is permeable to protons such that the hydrogen ions flow through the membrane and react with the oxidizer gas to form water. The membrane does not conduct electrons and therefore the electrons flow from the anode to the cathode to complete a circuit.
The catalyst material on the anode and cathode and the membrane is highly susceptible to poisoning from impurities in the hydrogen fuel source. These impurities may be present in the chemical feedstock and/or be introduced into the hydrogen during storage and/or delivery to the storage facility. Depending on the species of the impurity and/or the concentration of the impurity, the fuel cell may be permanently damaged due to a single exposure to impurities in the hydrogen fuel source.
Since conventional polymer electrolyte fuel cells are highly susceptible to poisoning from contaminants in the hydrogen fuel, it has been suggested that a fuel cell type electrochemical device may be used as an analyzer to detect the presence of contaminants in a fuel source before delivery of the fuel to the fuel cell. However, fuel cells require water to maintain membrane humidification, which improves membrane ion conductivity and increases performance of the fuel cell. In many conventional fuel cells, the hydrogen fuel source and oxidizer are actively humidified with water to maintain membrane humidification. However, water is considered a potential fuel cell fuel contaminant and hydrogen fuel quality standards set a limit on the amount of water that may be present in the hydrogen fuel. Accordingly, actively humidifying the hydrogen fuel source with water precludes the use of conventional fuel cells as a fuel quality analyzer because water itself is a fuel cell contaminant.
Additionally, operators of hydrogen filling stations could periodically test hydrogen quality, but the levels of impurities would require extractive methods using high-precision analyzers (e.g., gas chromatographs, cavity ring down spectrographs, etc.) that would be expensive and require highly-skilled operators. Additionally, a timely test result within minutes is desirable; otherwise, the time delay (e.g., caused by shipping the sample to be tested at a laboratory) could expose many fuel cell vehicles to contamination before the impurities at the hydrogen filling stations are detected.